In case you are wondering "how did we get here exactly?" Let me outline some things.
Playgrounds and play areas in fast food and malls required more employees to keep them clean. People (fairly) didn't want to do that work for minimum wage on top of their normal restaurant duties, and stores wouldn't hire enough people to not have to split work between the kitchen and cleaning. So the play areas were closed off and then torn down.
Then, apple came in with their empty white box stores, and suddenly everyone wanted to look like them (because they had a massive hit product that was also a status symbol and people want to feel like they have status even if they don't) or like a luxury brand store (again, false status). Bright white, extra white LED lights everywhere (nice in some ways, but blinding in others), fewer items stocked on shelves and then in general in stores. Apple had that design in part because they had relatively few products to display relative to store size, same with luxury brands. It makes more sense for each item to be on a pedestal when you only sell a handful of products. It doesn't when you have dozens of products.
At your more "middle class" stores, part of shift to stocking less is false scarcity - they want people to feel like they have to buy an item now or risk not getting it, and so people can't wait for discounts. Part of it is that with the new displays that hold fewer items but make things look more "boutique," keeping the shelves stocked and things moved from the back requires more employees than they are willing to pay. My local target, which is undergoing renovations to better fit their "Target Boutique" look, has had chronically empty shelves in some areas due to understocking and not having enough staff to replenish stock in all areas. Now they've added more self checkouts so they can cut back on cashiers and move those jobs to stock. Some places that haven't gone as "minimalist", like Walmart, have also shifted their employment focus from cashiers and stock to mainly stock by switching to primarily self checkout in efforts to maximize profits by reducing labor costs.
Part of getting rid of fun, unique designs was also reducing costs to make profit rather than innovating or drawing more customers to increase revenue. Custom molded seats with several different designs cost more than a minimalist set of identical chairs. Anything that children can play with or play on will break eventually and need to be replaced, so it's cheaper to just not have those things and not have to spend money on them. Unique roofing and siding costs more money to replace, so it was swapped for generic stock. If it can't be pressure washed or painted over, then it's also out because those are the cheapest ways to clean or refresh the storefront. Fountains break down, so rip them out or don't have them to begin with. Landscaping requires maintenance, so just leave it plain concrete and don't bother with planters. If there are plants, they will be knock-out roses, box hedges, and maybe some small cheap annuals because the former require next to no maintenance and are disease, pest, and pollution resistant, and the later just get replaced with other cheap annuals the next season. In the name of profit, everything looks bland and repetitive.
In the 90s and early 2000s, the middle class has more spending power to balance out the costs of fun and family friendly things in public spaces, but also percent profit hadn't needed to grow as much for a company to call itself successful. Because total profit isn't what matters, what matter is percentage profit growth. When you want your profits to grow exponentially, you have to minimize costs exponentially also - which, eventually, will lead to a collapse because there is a minimum you have to spend to operate and have people willing to work and want to pay for your product.
(There is also a back-and-forth relationship between residential and commercial design, outside of just where mandated by towns, where commercial mimics residential in an effort to feel "homey" and "inviting" and then people go "ew, that house has the same exterior as the mcdonalds. I don't want my house to match fast food," so the housing shifts to something else, and then the commercial design shifts again, and this goes on forever and no one learns to just make the businesses unique because that would impact their profit growth)
The "boutique" look of stores also serves another purpose. By having some items scattered in various sections (accessories being mixed in with the clothing sections rather than in a separate accessories/jewelry section, some pet goods are in the pet section, others are in seasonal or sport or housewares, etc.) you force people to walk through areas they normally wouldn't in order to find a specific item they are looking for. If I want a sun hat for my beach trip, I can't just go to hats, get the one i want, and then be done. I have to walk through swimwear where they've also placed some beach towels and pool floats and water bottles, because they hope I will impulse buy the other things if I'm there for only one of them. This is the same reason the grocery store keeps getting seemingly arbitrarily rearranged every 6 months. It is arbitrary, and it's because they want people who have a routine of shopping for their staples and know exactly where they are, thus overlooking other items, to have to look at the shelves more closely again, which makes them more likely to make impulse purchases.
Anyway, as usual, the question of "why does shit suck and why is nothing as fun as it used to be" is answered by "capitalism."